Pulverized fuel combustion system



Patented Mar. 8, 1927.

UNITED STATES CHARLES W. E. CLARKE, F NEW YORK, N.` Y.

PULVERIZED FUEL COMBUSTIO SYSTEMS,

Application filed. November 10, 1923. Serial No. 673,920.

This invention relates te apparatus for burning powdered fuels,hereinafter for convenience referred to as coal.' The advantages ofburning coal in a powdered or pulverized condition have commendedthemselves so strongly to Steam power plant engineers, that this type ofcombustion system is going into use very rapidly. Such systems, however,requires ay preliminary treatment of the coal at the plant in which itis to be burned, and the present `invention is concerned particularlywith this preliminary treatment or preparation of the coal.

Usually this preparation includes the drying and pulverizing of thecoal, the exact nature of the treatment varying somewhat with theconditions in individual plants. Such preparation, however, has usuallynecessitated two or three handlings of the coal, and'has required theuse ofv an auxiliary coal treating plant which occupies considerableHoor space and represents a substantial initial investment.

It is the chief object of the present invention to effect economies inthe preliminary treatment or preparation of the fuel. The invention aimsespecially to reduce the number of handlings of the coal required, andto devise an lapparatus which will handle the coal more economically,will occupy less floor space, and will be cheaper in initial cost thanapparatus heretofore used for this purpose.

The nature of the invention will be readily understood from thefollowing description when read in connection with the accompanyingdrawings, and the novel features will be particularly pointed out in theappended claims.

The single figure of the accompanyingdrawings is-a diagrammatic viewshowing the general arrangement of a coal handling apparatus embodyingthe present invention.

The drawings show a boiler installationV of a known form comprising twoboiler units arranged back to back. In the right-hand unit, 2 designatesthe furnace, 3 the water tubes of the boiler, 4 the uptake for the fluegases, and 5 the stack into which the gases are discharged. Pulveri'zedcoal is fed to the furnace from a pulverized fuel bunker or bin 6 bymeans of a feeder 7 which forces the coal into a pipe S that conducts itto the burner 9. The corresponding elements of the left-hand unit areindicated by primed numerals corresponding to those which designate theelements just referred to. All the parts so far described areconstructed, arranged, and operate in a well known manner.

According to vthe present invention, a green coal bunker 12 is locatedabove the furnace and at a higher level than the powdered fuel bunker 6.`The crushed green coal is delivered to this bunker 12 by any suitableconveying or elevating mechanism, as, for instance, by abelt conveyor,bucket conveyor, orv the like, the upper end of such a conveyor beingindicated at 14e. In the arrangement shown, the elements of the treatingor preparing apparatus are arranged in duplicate. These elementscomprisetwo dryers 15 and 15 into which the coal feeds by gravitydirectly from the bottom of the bunker 12. These dryers are arranged tobe heated by waste heat or flue gases from the furnace, .and for thispurpose a wind trunk or conduit 16 leads gases from the stack 5 to thedryer15, while another trunk or conduit 17 conducts these gases from thedrier to the intake end of a blower 18 which forces them through an eX-haust pipe 19 back into the stack 5. The circulation of gases throughthe dryer of course is created by the blower. Corresponding connections,indicated by primed numerals, are providedv for the opposite dryer 15.These dryers may be of a known type, consisting of alternate coal andair spaces separated from each other so that the coal is spread out inrelatively-thin streams as it passes through the dryer.

From the dryers 15 and 15 the coal passes directly by gravity intopulverizers 20 and 20', respectively. The coal in the pulverizer 2O isnext run through a pneumatic separator, commonly called a cycloneseparator. That is, it is picked up in a current of air created bytheblower 21 and forced into a separator 22. From this separator the coaldrops by gravity either directly into a pulverized coal bunker 6, orelse into distributing screw conveyors 24 which deliver it to thepulver-ized fuel bins or bunkers.

It will now be evident that this arrangement requires but a singlehandling of the coal, the green coal being delivered directly to a greencoal bunker which is so located that gravity is utilized thereafter todeliver the coal from one treating unit to the next. Not only' is thehandling of the coal, therefore, made more economical, but the initialcostrofftherl` treating or :preparation Vplant is lf2 the ,Wreenfcoal byviraste fluegases'fifom the,4

f boiler furnaces.

wlVliile l .have flierein shownK andedeseribed a preferred embodiment ofmy invention,y

it. will; beb understood that' the farrangementl l ofthe-elements Iof=the treating .plant ,necessari-ly Willadepend to somegextent'upon` the;-tles.ign,` locationA and arrangementof fthe powergpla-nt with; Whiclrthe treating#ap-2` yeparatus. isvito ybewusedeand also with the 'na-yl'f .y ture Vofhgthef treatment or preparation. which;

:the ifuel is 'tofundergo The invention there-ll fore. may be embodiedinf'many forms-Withrout;` departing yfrom: `the spirit or ,scopeffthereof.

2 @Havingthus described myinventionywhat i f I fdesire 4t'owrlaimi :asnew is:

1-.In ag powderedy fuel combustion sys tem7 the Acombi'iiationzofa'furnace, agreen coal bunker mounted abovef vsaiclj furnace,

amfnieans'` for' feeding coalgto theafurnace, ,andi

coal i Y- treatingf apparatus; `located between said feeding. means andsaid bunker, `said rapparatus:including a pulverizer into Whiclr l 'theo oal is fedby gravity from said bunker;y

2i. In apowderedffuel combustionsystem, -the combination fof, a furnace,afpulverized;y frelwbunkeiymeans forfpfeedingcoal from. said bunkertothe `furnace,` al green `Coal lainkerI ,located above the level fofisa-id' pow- 4coal bunker,.locatedE above said` :furnace7 4U: deredfuelbunkenand coal treating-appar; tusthrougli 4wh-ichthc coal is fedfrom 4said fgifeen coal bunker to said pulverizedfuel bunker,4saideapparatus including;I treating*` units to which the coal is `fedbygravityy from said green eoal bunker.

3. In aipoivderedfuel coinbuation system. the -coi'nbination of afurnace, ay pulverized ,.fuelibunlreigemeans:for feeding `coal from:said bunkerl Ato thegwfurnaeea a-green `eoal rbunlier 'located abovethe.-` level of, Lsaid powderedwfuel bunker;` a; dryer into which igreencoal is fed bygravityfrom-[said green coal bunker, said dryer beingarranged to be heated vbyfluemgases from said furnace,

gravity., from `Said dryer, a pneumatic separator through which the coalis passed from lsaid'.-pulverizeiy..and means for utilizing gravity inconducting the coal from said Vseparator` Ato :saidpulverized. coalbunker.

4.1111; aapewdered fuel combustionasys- ,-tem,;the combination-of afurnace, Egreen i coal-.bunker located abovesaid furnace-,Janyeleifatorzfor delivering coal to :said bunker,

a-dryer-aiutol which lsaidagreen coal is-argranged-- Avto I be -ffed \bygravity ifromqsaid bunker, said f "dryery :being arranged.to` f be:heated by flue gases from said furnace, a pjulverizerinto which. thecoal f Hows-by gravityfrom said dryer5 a pneumaticA sepa.- rator through'Whichfhe coal is; discharged from A said.pu-lverizer,V a;,Apu'lverizede'fuel bunker.; located. belowv said l Yseparatorl andAinto4 which .thegeoal isdisoharged fromV the separator-by grav-itaind4means 'for conducting` coal from A"said lpulverized I' fuel bunker to iAsaid .-furnace f 5.5ln a` powderedfuel combustionsystem,

the combination 4of ajfurnace a greenel bunler mountedabove-saidfurnace, means .for-i feeding-coalto the furnace` and coal treatingapparatus located v^-vrbetiweensaid feedingmeansl andsaid-bunker; lsaidapparatus-ineluding a vdrierein'to- `Whichtliecoal is fed byfg-ravityfrom .saidbugnler and a pulverizer vintoavhielr the coalpassesV bygravity from said ldrier.

6J ln a .po'ivderedwfuel combustion .systemy-the` combination ofafurnace, a green vmeans for deli-vering' coalftoysaid.bunker, a drierinto which said green coal is arranged ytobe fed by gravity .fronrsa-id.bunker, a pulverizer Linto which .the .coalA flows by gravity fronmsaiddrieig` al,.pneumat-ie-sepatrator.-.fthrough whichthe,.eoaleis;discharged from saidvrpulverizer, and ,means located belowsaid separator for conducting the-.coal

A,fr@nm-said, separator to.said furnace.

i goHABLESLW. CLARKE.

